Process for introducing alkali or earth-alkali metals in discharging tubes and the like



March 4 1924;

PROCESS FOR INTRODUCING ALKAL 1,485,505 G. HOLST ET AL I OR EARTH ALKALI METALS IN DISCHARGING TUBES AND THE LIKE Filed Oct. 26 1920 Jul/ems.-

% Wtw JMwwe J Patenlted Mar. 4, 1924.

UNITED STATES PATENT OFFICE.

GILLES HOLST AND mo OOSTEBHUIS, OI EINDHOVEN, NETHERLANDS, ABBIGHOM T0 NAAMLOOZE VENNOOTSCEAP PHILIPB GLOEILAIPIDI-FABEIEKEN, OI BIND- KOVEN, NETHERLANDS.

PROCESS FOR INTBODUUING ALKALI OB mam-sum III-TALE IN DIBGKABGING TUBES AND THE LIKE.

Application fled October 86, 1990. Serial Ho. 418,859.

To all whom it may concem;

Be it lmown that we, GILLES HOLBT and EKKO Oosrnnmns, both sub'ects of the Queen of the Netherlands, resi ing at Eindhoven, in the Province of North Brabant, in the Kingdom of the Netherlands, have invented certain new and useful Improvements in a Process for Introducin Alkali or Earth-Alkali Metals in Disc arging Tubes and the like (for which I have le an application in Kingdom of the Netherlands on September 23, 1919, -Serial No. 12966, Ned.), of which the following is a specification.

This invention relates to vacuum or discharge tubes (incandescent lamps, X-ra tubes, audions, rectifiers, etc.), bem 'vesse s used electrically and exhausted 0 air to form a vacuum, or filled with suitable gases at or below atmospheric pressure. For want of a suitable generic term such devices will be herein referred to as evacuated container electrical apparatus, or evacuated containers.

It is known, that substances such as calcium, barium, strontium, potassium, sodium etc., in gaseous condition combine with all gases except the noble ases, whereby compositions are formed w ich have ver low vs r pressures. This action is great y acce erated by electrical discharges.

In such evacuated containers all gases resent or set free, except the noble gases will quickly disa pear in the presence oi said metals, so t at a hi h vacuum or a very ure noble gas filling is obtained.

It as already on proposed to use heated earth-alkali metals for the absorbing of gas residues (German Patent 179526).

It has also been dproposed in dischar 'n tubes to use electro es com osed of an al ka 1 metal or an alkali metal al oy (French Patent 451846, British Patent 29104/1912). Though in this case the alkali metal also absor eventual gas residues, yet the principal function of the alkali metal is to coact in the discharge. According to these atents the alkali metal is used for decreas- 1n the tension of dischar Therefore the cat ode must consist whol or for a lar part of an alkali metal, an the decrease of the discharge tension would cease when all The invention consists in introducing alkali or earth alkali-metals in such evacuated containers in order to remove the last 7 gas residues or to purify noble gases; it is characterized by this, that in the tube or the like an allow of an alkali or earth alkali metal (such as potassium or calcium) with a noble metal of low vapor pressure (such as tin) is applied at a place where a sufliciently high tem rature is obtained to vaporize the alka 1- or earth alkali metal, whereas the other component of the alloy does not evaporate to a erce tible extent.

As the only object of t e al all or earth alkali metals is to absorb small quantities of gases present or-set free, only very small quantities of these metals are necessary, because they may be used up when no more gases are set free.

When applying the lprocess according to the invention one shou d take care that the alloy is not put in places where the vapor of the alkali or earth alkali metal might acquire such a tension, that it would take part in the discharge.

The following are examples of "suitable alloys for the practice of the present invention:

1. Tin, 96%, calcium, 4%.

2. Tin, 95.7%, potassium, 4.3%.

The use of and alloys has several advantages. In the first place the active metal is protected by the noble'r metal against oxidation, moisture and other influences. At the same time the handling of. these active metals is thereby without any dan r. v A further advantage is, that the a loy may be put into the container in a very sim le way. If one uses for instance a tin al oy this may be used as a solder upon one of the metal parts in the tube.

The aooo an g drawing shows one 8 way in whi dii t d invention may be applied, Fig. 1 being an elevation of a discharge tube; Fig. 2 an elevation of the cathode part thereof; Fig. 3 an elevation of the anode; and Fig. 4 an'elevation of the anode art.

In t ese drawin a is the anode which consists of a cylin rical plate upon WhlCh the alloy is applied on a small area on the outer side; the cathode wires are melted in the glass at b and the anode wires at c. The illustrated construction is given merely as anexample, "the in'vention not bein char tube or other analogous structure.

W at we claim is:

1. Evacuated container electrical apparatus, in which an alloy of an alkalior earth alkali-metal with a nobler metal of low vapor ressure is applied at a lace where a sufficiently high temperature 15 obtained to directed to any particular constructi n 0 the (118- vaporize the alkali or earth-alkali metal, while the other component of the alloy does not evaporate perceptibly and the vapor of the alkali or earth alkali metal does not coact in the conduction of the current.

2. Evacuated container electrical apparatus, in which a tin-calcium alloy is applied at a place where a sufiiciently hi h temperature is obtained to vaporize t e calcium while the tin does not evaporate perceptibly and the calcium-vapor does not coact 1n the conduction of the current.

In testimony whereof we have hereunto set our signatures in the presence of a witness.

GTLLES HOLST. EKKO OOSTERHUIS. Witness:

AMAN NAGTEGRALF. 

